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TMS320F28388D: EtherCAT automatic polarity detection ( TX/RX)

Alexis Maslyczyk
Prodigy 175 points

Part Number: TMS320F28388D
Other Parts Discussed in Thread: TMDSCNCD28388D

Hi all,

I have not been able to find the information. I have two slaves on EtherCAT, what should be the proper way to daisy chain them.

I have seen some design going from TX to TX, some TX to RX (which make more sense to me). Could you please confirm both will work?

I know some EtherCAT controllers such as LAN9252 are smart and detect the which one is TX and which one is RX so it does not matter, but what about the F28388D. 

Thank you

  • 0
    TI__Mastermind 45606 points

    Hi Alexis,

    Are you using two TMDSCNCD28388D boards? You would connect in the following way:

    • Port 0 of F2838x Slave 1 connects to TwinCAT PC
    • Port 1 of F2838x Slave 1 connects to Port 0 of F2838x Slave 2
    • Port 1 of F2838x Slave 2 remains open / unconnected

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    Prodigy 175 points

    Hi Kevin,

    I am not asking for the Port, I am asking for TX-RX connections.

    It is for custom boards design not TMDSCNCD28388D related but for example, if we take two TMDSCNCD28388D and connect them using standard ethernet cable, pin 1 is connected to pin 1

    So this means, you connect

    TXP_PORT1 (slave 1) to TXP_PORT0  (slave 2)

    TXN_PORT1 (slave 1) to TXN_PORT0 (slave 2)

    RXP_PORT1  (slave 1) to RXP_PORT0 (slave 2)

    RXN_PORT1  (slave 1) tp RXN_PORT0  (slave 2)

    But in EtherCAT documentation you can also find diagrams where TX is not connected to TX but to RX! This create confusion, my question is: does it really matter?

    Thank you

  • +1 in reply to Alexis Maslyczyk
    TI__Mastermind 45606 points

    Hi Alexis,

    For the phyiscal layer what will really matter is the PHY signals that get connected to each other (before/after the cable). The 2nd graphic you show is more for conceptual understanding I believe.

    I recommend referencing the PHY device datasheet you are using to better understand the TX/RX connections that need to be made.

    Best,

    Kevin